AFS Foundry Sand Testing Equipment Operating Instructions Manual

RIDSDALE-DIETERTRAPID SAND WASHER (Type N) (cont’d)IIIINSTALLATIONConnect the control box to an appropriate power supply (see name plate on motor for correctvoltage and frequency). Plug the stirrer unit into the control box. Place a wash beaker inposition in the metal stand and check the length of the syphon tube by moving the clip sothat the curved end of the tube is 25 mm above the bottom of the beaker. Remove the tubefrom the beaker.IVTEST PROCEDURE(a) Take a representative sample of moist sand weighing approximately 50 g.(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)(l)(m)Dry the sample, weigh accurately and place in the wash beaker.Add 475 ml distilled water at room temperature and 25 ml of 1.5% w/v tetrasodiumpyrophosphate solution (now recommended by the AFS as a deflocculant instead ofsodium hydroxide, which has a tendency to cause gelling problems preventing sandgrains from settling properly).Place the stirrer unit in the wash beaker.Check that the “Continuous” switch on the control box is off, and switch the “Mains”switch on.Set the agitation period to 5 minutes by rotating the time switch to its maximumposition and then back to the figure 5.When the 5 minute period has elapsed and the motor stops, disconnect from thecontrol box. Remove the stirrer unit from the beaker, wash any sand grains whichmay adhere to the vertical baffles or agitator back into the beaker with distilled water.Fill the beaker with distilled water to the top line in such a manner that the contentsare well stirred. Remove the beaker from the stand.Set the settling time on the control box at 10 minutes and switch the “buzzer” switchon.When the alarm indicates that the first 10 minute settling period has elapsed switch itoff, fill the syphon tube with water, place a finger over the end of the straight sectionand insert the curved section into the beaker. Remove finger and syphon clay/watersuspension out of the beaker.Fill the beaker to the top line with distilled water, stirring the sediment on the bottomand allow to settle for a second 10 minute period.Syphon off the suspension when the alarm indicates that the 10 minute settling timehas elapsed. Refill to the top line, allow to settle for 5 minutes and syphon off thesuspension.Repeat the process of 5 minute standing and syphoning until the water is clear at theend of a 5 minute settling period.Syphon off the clear water and decant as much of the remaining water as possiblewithout losing any sand grains.3